Forehearth.



No. 856,616. PATENTED JUNE 11, 1907.

' G. M. ALLEN.

FORBHEARTH.

APPLIIOATION rum) IA! 25. 1904.

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No. 856,616. PATENTED JUNE 11, 1907. C. M. ALLEN.

PORBHEARTH.

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UNITED STATES PATENT OFFICE.

(HARLES MAURICE ALLEN, OF LO LO, MONTANA, ASSIGNOR TO RALPH BAGGALEY, OF PITTSBURG, PENNSYLVANIA.

FOREHEARTH.

Specification of Letters Patent.

Patented June 11, 1907.

To all whom it may concern:

Be it known that I, CHARLES MAURICE AL- LEN, of Lo Lo, Missoula county, Montana, have invented a new and useful Forehearth, of which the following is a full, clear, and exact description, reference being bad to the accompanying drawings, forming part of this specification, in which Figure 1 is a plan view of my novel forehearth. It also shows in outline a coppersmelting furnace which discharges into the forehearth; Fig. 2 is a side elevation of the parts shown in Fig. 1.

The object of my invention is to conserve the heat of the molten contents of the forehearth and by this means to prevent filling of the forehearth with chilled material; to prevent the escape of the molten material through the side walls of the forehearth and to eliminate the present heavy expense for repairs.

filling of the forehearth with chilled material,

so that it finally becomes necessary to cease active operations altogether for a sufficient length of time to admit of the removal of such solidified masses. It has also been proven in practice that where the walls of the forehearth are not water-cooled, the brick or other such material heretofore used to form the lining gradually dissolves, so that it becomes necessary from time to time to cease operations long enough to admit of a new and expensive lining being supplied. I have overcome all of these difficulties and have produced a forehearth that is practically indestructible and does not fill with chilled material; and this I accomplish by forming the side walls of the forehearth of heavy metal blocks, which absorb, retain and conserve the heat of the molten slag and matte. It is recognized that where water is used as a coollng medium for the protection of the fore hearth walls a constant circulation must be maintained in order to prevent it from being converted into steam and thus quickly dissipated. All efforts thus farto reduce the flow, even to the extent of holding it to a point of continuously throwing off steam, as a means of increasing its temperature and thereby moderating its chilling influence on the molten charge, have been unsuccessful.

The entlre wall of the water acket must at all times be in actual contact with the body of water for the preservation of the jacket, for steam affords no substantial protection, and if the water in the jacket is allowed to become hot enough to boil, the jacket will be burned. At the sea lever water boils at 212 F., and its temperature cannot be increased above this point unless it is held under pressure. Therefore this point represents the limit of heat of the water in any jacket as it is not practicable to maintain a steam pressure therein.

Heavy blocks of metal are not subject to suddenly varying temperatures. They require time to absorb heat and as soon as the molten charge is delivered from the furnace into a forehearth composed of such heavy blocks, a skull of the molten material itself is instantly formed over the entire inside surface of the blocks, because of the chilling effect that they instantly exercise upon it. This skull is an excellent non-conductor of heat and it has the double effect of retaining the heat in the molten bath and of subsequently protecting the metal blocks. The heat of the molten bath travels slowly through this interior skull and then passes into the blocks disseminating itself throughout the entire mass thereof. These walls therefore continuously absorb, retain and conserve the heat of the molten material at a nearly constant point so long as they are called upon to do so. This is in marked contrast with forehearths heretofore used and it is in especially marked contrast with the action of forehearths built with thin waterjackets. In the latter the temperature is constantly changing by reason of the varying flow and varying temperature of the water itself. A great difference must result, for instance, between the cooling effect of a jacket in winter and its cooling effect in summer.

In constructing a forehearth in accordance with my present invention, the thickness and weight of the metal blocks must conform to the volume of molten material that they are intended to contain without injury to themselves and without dissipating the heat of the material. The thickness must be such that when the forehearth is filled with molten material from the furnace the outside surface of the metal blocks Will be materially cooler than the inner surface. The drawings are made to the scale Which I deem preferable, and Will guide those Who wish to practice my invention.

In the drawings, 2 is the smelting furnace, and 3 is my novel forehearth into Which the slag outlet 4 of the furnace discharges, and which is provided With the usual overflow spout 5 and matte tap-hole 6. The side Walls of the forehearth are composed of thick metal blocks 7 of iron, steel or copper, preferably fitted together with tongues and grooves 8 and secured by bolts through bolting flanges 9.

The construction may be modified since What I claim is:

1. A forehearth having its Walls of a size, Weight and mass that Will produce and maintain an interior skull of chilled metal forming a heat non-conducting lining when the forehearth is charged and capable of retaining suflicient heat to prevent increase in the hearth is charged, substantially as described.

3. A forehearth having a skull of chilled metal on its inner face, the Walls of the forehearth being of a thickness to produce the skullon the introduction of the molten metal and also to retain sufiicient heat to prevent increase of the thickness of the skull, substantially as described.

In testimony whereof, I have hereunto set 40 my hand.

CHARLES MAURICE ALLEN.

Witnesses:

IRVING MAonoNALD, J. O. WOLFRAM. 

